I've been searching the web for some good info on this. An animated diagram would be great.
When you're bent over in the drops, are you using your glutes more than when you're on the hoods? And does that add to your speed as much as the increased aerodynamics?
And if you're very upright, like on a comfort bike, do you use your lower back muscles (like maybe the iliopsoas) more?
I had also read somewhere that climbing in the drops a lot could cause your back to hurt, but why? What muscle is straining here? When I want to go fast on my mountain bike, I try and hunker down real low and that's when it feels like my butt is getting more of a work out, so it seems like it would be better to climb hills in a bent over posture, too, so that I can make better use of the stronger glutes.
Anybody have any insights on this?